Full text of "USPTO Patents Application 10597633"

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WORLD INTELLECTUAL PROPERTY ORGANIZATION

International Bureau

PCT

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)

(51) International Patent Classification 6 :
A61N 1736

(11) International Publication Number:

WO 98/37926

(43) International Publication Date: 3 September 1998 (03.09.98)

(21) International Application Number: PCT/US98/03687

(22) International Filing Date: 25 February 1998 (25.02.98)

(30) Priority Data:

60/039,164

26 February 1997 (26.02.97) US

(71) Applicant (for all designated States except US): ALFRED E.

MANN FOUNDATION FOR SCIENTIFIC RESEARCH
[-/US]; 12744 San Fernando Road, Sylmar, CA 91342 (US).

(72) Inventors; and

(75) Inventors/Applicants (for US only): SCHULMAN, Joseph, H.
[US/US]; 16050 Comet Way, Santa Clarita, CA 91351
(US). DELL, Robert, Dan (US/US]; 19315 Old Friend
Road, Canyon Country, CA 91351 (US). GORD, John, C.
[US/US]; 806 Indiana Avenue, Venice, CA 90291 (US).

(74) Agent: FREILICH, Arthur; Freilich, Hornbaker & Rosen,
Suite 840, 10960 Wilshire Boulevard, Los Angeles, CA
90024-3704 (US).

(81) Designated States: AL, AM, AT, AU, AZ, BA, BB, BG, BR,
BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB. GE,
GH, GM, GW, HU, ID, IL, IS, JP, KE, KG, KP, KR, KZ,
LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW,
MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK. SL,
TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW, ARIPO
patent (GH, GM, KE, LS, MW, SD, SZ, UG, ZW), Eurasian
patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European
patent (AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT,
LU, MC, NL, PT, SE), OAPI patent (BF, BJ, CF, CG, CI,
CM, GA, GN, ML, MR, NE, SN, TD, TG).

Published

With international search report.

(54) Title: BATTERY-POWERED PATIENT IMPLANTABLE DEVICE

(57) Abstract

This invention is a device configured for implanting beneath a patient's skin for the purpose of tissue, e.g., nerves or muscle,
stimulation, and/or parameter monitoring, and/or data communication. Devices in accordance with the invention are comprised of a sealed
housing (110), typically having an axial dimension of less than 60 mm and a lateral dimension of less than 6 mm, containing a power
source (104) for powering electronic circuitry within, including a controller (130), an address storage means (132), a data signal receiver,
and an input/output transducer.

FOR THE PURPOSES OF INFORMATION ONLY
Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.

Albania

Spain

Lesotho

Slovenia

Armenia

Finland

Lithuania

Slovakia

Austria

France

Luxembourg

Senegal

Australia

Gabon

Latvia

Swaziland

Azerbaijan

United Kingdom

Monaco

Chad

Bosnia and Herzegovina

Georgia

Republic of Moldova

Togo

Barbados

Ghana

Madagascar

Tajikistan

Belgium

Guinea

Hie former Yugoslav

Turkmenistan

Burkina Faso

Greece

Republic of Macedonia

Turkey

Bulgaria

Hungary

Mali

Trinidad and Tobago

Benin

Ireland

Mongolia

Ukraine

Brazil

Israel

Mauritania

Uganda

Belarus

Iceland

Malawi

United States of America

Canada

Italy

Mexico

Uzbekistan

Central African Republic

Japan

Niger

Viet Nam

Congo

Kenya

Netherlands

Yugoslavia

Switzerland

Kyrgyzstan

Norway

Zimbabwe

Cdtc d' I voire

Democratic People's

New Zealand

Cameroon

Republic of Korea

Poland

China

Republic of Korea

Portugal

Cuba

Kazakstan

Romania

Czech Republic

Saint Lucia

Russian Federation

Germany

Liechtenstein

Sudan

Denmark

Sri Lanka

Sweden

Estonia

Liberia

Singapore

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WO 98/37926 PCT/US98/03687

TITLE: BATTERY-POWERED PATIENT IMPLANTABLE DEVICE

BACKGROUND OF THE INVENTION
The present invention relates to devices configured
5 for implanting beneath a patient's skin and more particularly to
such devices incorporating a battery for powering electronic
circuitry for various purposes including tissue, e.g., nerve or
muscle, stimulation and/or parameter monitoring and/or data
communication .

10 Implantable devices for tissue stimulation (i.e.,

microstimulators) are known in the art. See, e.g., U.S. Patent
Nos. 5,193,539; 5,193,540;. 5,312,439; 5,324,316; 5,358,514;
5,405,367; 5,571,148, which are incorporated herein by reference.

Such known microstimulators are characterized by a

15 sealed housing which contains electronic circuitry for producing
small electric currents between spaced electrodes. By precisely
implanting the microstimulators proximate to targeted tissue, the
currents will stimulate the nerve to produce medically beneficial
results .

20 Typically, such prior microstimulators derive

operating power from an internal coil that is inductively coupled
to an external AC magnetic field produced, for example, by a drive
coil mounted proximate to the microstimulator . An AC voltage
induced in the internal coil is rectified and filtered to produce

25 a DC operating voltage which is used to power the electronic
circuitry. Such an arrangement requires that the user remain in
close proximity to the drive coil to maintain tissue stimulation.
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WO 98/37926 PCT/US98/03687

SUMMARY OF THE INVENTION
The present invention is directed to a device
configured for implanting beneath a patient's skin for the purpose
of tissue, e.g., nerve or muscle/ stimulation and/or parameter
5 monitoring and/or data communication. Devices in accordance with
the invention are comprised of a sealed housing, preferably having
an axial dimension of less than 60 mm and a lateral dimension of
less than 6 mm, containing a self-contained power source capable of
supplying at least 1 microwatt-hour to power consuming circuitry

10 for actuating an input/output transducer. The circuitry in each
device is preferably remotely addressable and includes a data
signal receiver and a device controller.

Depending upon the intended application of the
device, the power consuming circuitry can be designed to demand a

15 high load current for a relatively short interval, e.g., for
bladder stimulation, or a lower load current for a much longer
interval or continuously, e.g., for bone growth stimulation. In
accordance with the invention, a power source in accordance with
the invention has a capacity of at least 1 microwatt-hour which for

20 a typical application is able to power the circuitry for over one
hour, thus liberating the user from having to be continuously
coupled to an external field generator.

In accordance with a significant aspect of the
invention, the power source comprises a battery, preferably formed

25 by a pair of conductive plates having electrolyte disposed
therebetween. The battery is preferably physically configured to
minimize eddy current formation.

In accordance with a preferred embodiment of the
30 invention, a charging circuit is provided for recharging the
battery. The charging circuit is capable of producing a charging
current in response to an externally produced AC magnetic field.

In a further aspect of the present invention, an
external charger is used to periodically generate an AC magnetic
35 field for supplying energy to the aforementioned charging circuit
and one preferred embodiment includes means for generating a data

I. 1

WO 98/37926 PCT/US98/03687

signal representative of the status of the battery to the external
charger .

In accordance with a still further aspect of the
invention, an identification address is stored in each implantable
5 device used in a system, thus enabling individual devices to be
addressed. That is, the data signal receiver in each device will
respond to a data signal identifying the address stored by that
device to actuate the device input/output transducer.

The input/output transducer in accordance with the

10 invention preferably comprises at least one electrode. When used
for nerve stimulation, the controller supplies a sequence of drive
pulses to the electrode to stimulate adjacent nerves. When used
for parameter monitoring, the electrode is used to monitor an
electrical signal indicative of certain body conditions.

15 In accordance with a significant feature of preferred

embodiments of the invention, each implantable device can be
individually addressed and programmed to selectively operate in one
or more of the following modes: (1) stimulation, (2) monitoring,
and/or (3) communication.

20 The novel features of the invention are set forth

with particularity in the appended claims. The invention will be
best understood from the following description when read in
conjunction with the accompanying drawings.
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WO 98/37926 PCTYUS98/03687

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a block diagram of a
microstimulator as known in the prior art;

FIG. 2 comprises a block diagram of the device of the
5 present invention including a battery for powering the device for
a period of time in excess of one hour in response to a command
from an external controller;

FIG. 3A is a simplified functional block diagram of
the use of the implanted devices of the present invention
10 (microstimulators, microsensors and microtransponders ) in an
environment where they are recharged and controlled from devices
external to a patient's body;

FIG. 3B shows a simplified timing diagram showing
periodic breaks in the generation of the charging magnetic field to
15 selectively interrogate the battery status of the implanted
devices ;

FIG. 4 is a simplified diagram showing the basic
format of data messages for commanding/interrogating the implanted
microstimulators, microsensors and microtransponders of the present
20 invention;

FIG. 5A shows a side view of a battery-powered
implanted device, e.g., a microstimulator, made in accordance with
the present invention;

FIG. 5B shows a side view of another implantable
25 battery-powered device, one employing an internal coupling
capacitor, made in accordance with the invention;

FIGS. 5C and 5D show two side cutaway views of the
presently preferred embodiment of an implantable device mounted in
a ceramic housing;
30 FIGS. 6A and 6B conceptually illustrate parallel and

series connections, respectively, of the electrodes used within a
battery of a preferred implantable device;

FIG. 7A illustrates the general cylindrical shape of
the battery used within the preferred implantable device of the
35 present invention;
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WO 98/37926 PCT/US98/03687

FIG. 7B conceptually depicts the basic electrode pair
used within the battery of the implantable device of the present
invention;

FIGS. 8A-8G illustrate various configurations of
5 electrode wrapping, stacking, interleaving, or other positioning of
the basic electrode pair that may be used within a cylindrical
shaped battery of the present invention;

FIGS. 9A and 9B depict one manner in which the basic
electrode pair may be stamped, folded and interleaved for use
10 within a series-electrode battery configuration of the type shown
in FIG. 8C; and

FIG. 10 illustrates an exemplary waveform for drive
pulses produced by a preferred microstimulator showing the drive
pulse's low duty cycle.
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WO 98/37926 PCT/US98/03687

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a device
configured for implanting beneath a patient' s skin for the purpose
of tissue, e.g., nerve or muscle, stimulation and/or parameter
5 monitoring and/or data communication. Devices in accordance with
the invention are comprised of a sealed housing, preferably having
an axial dimension of less than 60 mm and a lateral dimension of
less than 6 mm, containing a power source and power consuming
circuitry including a controller, an address storage means, a data

10 signal receiver and an input/output transducer. When used as a
stimulator, such a device is useful in a wide variety of
applications to stimulate nerves and associated neural pathways,
e.g., to decrease or relieve pain, stimulate specific muscles or
organs to better carry out a body function (e.g., to exercise weak

15 or unconditioned muscles or to control urinary incontinence) , and
the like. Preferably microstimulators of the present invention are
individually addressable for control purposes via a magnetic, RF or
ultrasonic signal .

FIG. 1 shows an exemplary prior art implantable

20 stimulator 10 (as shown in FIG. 1 of the aforementioned U.S. Patent
No. 5,312,439) implanted beneath a patient's skin 12 that receives
power from an externally located power supply 14 via an alternating
magnetic field generated by an externally mounted coil 18 that is
energized by a transmitter 20. Within the stimulator 10, the

25 magnetic field generates an AC current in a coil 22 that is
rectified by rectifier 24 and stored in a capacitor 26 in
conjunction with a regulator 28 to generate a voltage that powers
its logic 30. The logic 30 is then used to generate a stimulation
current between electrodes 32 and 34. Since the control logic 30

30 relies upon power stored in the capacitor 26 to supply its
operating power, it typically stops functioning in a short period
of time after the external power supply 14 is removed as the charge
stored in capacitor 26 is depleted. Consequently, when such a
stimulator 10 is used in an application which requires continuous

35 stimulation, e.g., for blocking pain in a neural pathway, the
continuous presence and activation of the external power supply 14

WO 98/37926 PCT/US98/03687

is required. While such a continuous presence can be achieved by
use of a portable power supply, its physical presence can be
considered as a life style limitation.

In contrast, FIG. 2 shows a block diagram of an
5 electrically-powered implantable device 100 of the present
invention {configured as a microstimulator ) that can stimulate
tissue (e.g., a neural pathway or nerve) for a prolonged period of
time, i.e., in excess of one hour, without requiring the continuous
use of an external power source. Consequently, in an exemplary

10 application, a preferred microstimulator 100 can be used to block
pain in a selected nerve for a prolonged period of time, long after
the external power source has been removed. The microstimulator
100 of the present invention is comprised of a sealed housing 206
(see FIG. 5) for enclosing a power source 102, e.g., a rechargeable

15 battery 104, and power consuming electronic circuitry including (1)
controller circuitry 106 powered by the power source 102 and having
address storage circuitry 108 with an identification address (ID)
stored within, (2) stimulation circuitry 110 powered by the power
source 102 and operating under control of the controller circuitry

20 106 for providing drive pulses to one or more electrodes (i.e.,
transducers) 112, and (3) receiver means 114 for providing command
and address identification information to the controller circuitry
106.

In a preferred implementation, the power source 102
25 comprises a rechargeable battery 104 used in conjunction with a
charging circuit to provide sufficient power for prolonged
activation of the controller circuitry 106 and the stimulation
circuitry 110. However, embodiments of the present invention
alternatively use a primary battery in place of the rechargeable
30 battery 104, e.g., in applications where a treatment regimen is
relatively short term and thus, the power requirements are within
the power capacity of the primary battery.

In operation, a coil 116 receives power in the form
of an alternating magnetic field generated from an external power
35 source 118 (see FIG. 3A) and responsively supplies an AC current to
a rectifier 120 which is passed as a rectified DC current to a

WO 98/37926 PCT/US98/03687

charging circuit 122. The charging circuit 122 then monitors the
voltage V on battery 104 and charges it according to its preferred
charging characteristics (current and voltage) . As discussed
further below, the charging circuit 122 preferably communicates via
5 path 124 with the controller circuitry 106 which in turn
periodically communicates with the external power source 118 via a
magnetic, ultrasonic, or RF signal.

In a typical application (see FIG . 3A) , a plurality
of such devices 100, e.g., microstimulators, are implanted under

10 the skin 12 of a patient's body and simultaneously subjected to an
alternating magnetic field 154 from the external power source 118.
Accordingly, once the charging circuit 122 determines that battery
104 has been sufficiently charged, the charging circuit 122
preferably detunes coil 116, e.g, by shunting out centertap 126 (or

15 adding a capacitor across the coil), and thus minimizes any heat
generation in the charging circuit 122 or in the battery 104 from
overcharging. Thus, the external power source 118 can continue to
provide charging power via an alternating magnetic field
indefinitely. However in one preferred embodiment, the external

20 power source periodically polls the implanted devices for status
information and continues to provide charging power until it has
received status information from each of the implanted devices 100
that its battery 104 is charged.

Both the controller circuitry 106 (via power input

25 terminal 127a) and stimulation circuitry 110 (via power input
terminal 127b) receive power from the battery 104 power output
terminal 128. The power dissipation of circuitry within the
implanted device 100 is minimized by the use of CMOS and other
lower power logic. Accordingly, the required capacity of the

30 battery 104 is minimized.

The controller circuitry 106 controls the operation
of the stimulation circuitry 110 using a controller 130 (preferably
a state machine or microprocessor) according to configuration data
within a configuration data storage 132 coupled to controller 130.

35 The configuration data specifies various programmable parameters
(discussed further below) that effect the characteristics of the

WO 98/37926 PCT/US98/03687

drive pulses generated by stimulation circuitry 110 as controlled
by the controller 130. Preferably, each implanted device 100,
e.g., microstimulator, can be actuated (enabled/disabled) or have
its characteristics altered via communications with one or more
5 devices external to itself. Accordingly, each implanted device 100
uses its address storage 108, e.g., an EE PROM, PROM, or other
nonvolatile storage device programmed during manufacture, to
identify itself (e.g., using an ID code stored within of 8 or more
bits) . Alternatively, the address storage 108 can be comprised of

10 a portion of an integrated circuit that is mask programmed to form
all or a portion of the ID and/or the use of a laser trimming
process to designate all or the remaining portion of the ID. In a
further alternative implementation, the ID can be designated by a
selection of jumpers, e.g., wire bonds, used individually or in

15 combination with the use of a laser trimming process. In
operation, an external device (e.g., charger 118) transmits a
modulated magnetic, ultrasonic, or RF command signal containing
command information that includes an address field. When the
implanted device 100 receives and demodulates this command signal

20 to receive the command information within, it first determines
whether there is a match to its address within its address storage
108 before processing the rest of its data. Otherwise, the command
information is ignored.

In a first embodiment, alternating magnetic field 154

25 is amplitude modulated with this command signal. Receiver
circuitry 114a detects and demodulates this command signal by
monitoring the signal generated across coil 116 (preferably the
same coil used for charging the rechargeable battery 104) . The
demodulated data is provided to a controller data input 134 via

30 path 136 where its applicability to a particular implanted device
100 is determined. Alternatively, the command signal can modulate
an RF signal which can be detected in a similar manner by receiver
114a (configured to demodulate an RF signal) using coil 116 as an
antenna or using a separate antenna.

35 In a next embodiment, an ultrasonic signal can be

used to deliver this command signal to each implanted device 100.

WO 98/37926 PCT/US98/03687

In this embodiment, an ultrasonic transducer 138 located within the
device 100 generates a signal 140 which is demodulated by
ultrasonic demodulator 114b. This demodulated signal is then
provided to an ultrasonic data input 142 via path 144 and processed
5 in a manner similar to that described in reference to a magnetic
signal. The ultrasonic implementation provides significant
advantages in that a patient' s body is primarily comprised of fluid
and tissue that is conducive to passing an ultrasonic signal.
Consequently, a control device located anywhere inside (or external

10 but in contact with) the patient's body can communicate with each
device 100 implanted within.

In a preferred embodiment, the implanted device 100
includes means for transmitting status and data to external
devices. In an exemplary charging mode, it is preferable that each

15 device 100 can individually communicate with charger 118 so that
charger 118 can determine when all of the implanted devices 100
have been fully charged. Preferably, device 100 includes
transmitter means to emit a magnetic signal modulated with this
data. This transmitter means comprises modulator circuitry 146

20 which amplitude modulates an AC voltage and delivers this modulated
signal to coil 116 which emits a modulated magnetic signal. While
this modulated signal can use a different carrier frequency from
that of the AC signal used by the charger 118, it is preferable
that the communication channel, i.e., the magnetic field 154

25 between the devices, be time-shared as shown in FIG. 3B . In FIG.
3B, the charger 118 emits an alternating magnetic field for a first
time period 148. At the end of the first time period 148, this
alternating magnetic field is modulated (e.g., amplitude modulated)
with a series of bits corresponding to polling data corresponding

30 to a selected microstimulator 100 (i.e., including an address for
one implanted device) . The charger 118 then goes into a receive
mode for a second time period 150 during which time the selected
device 100 emits a magnetic signal modulated with a series of bits
corresponding to its battery status. This charging/polling cycle

35 preferably repeats for all of the implanted devices within the
operational range of the charger 118. Once the charger 118

WO 98/37926 PCT/US98/03687

determines that all of the devices 100 have been charged, the cycle
is terminated and the patient or clinician is preferably notified,
e.g., using a visual or audio annunciator 152.

Alternatively, ultrasonic means can be used to
5 communicate status or other data from the implanted device 100 to
an external device. In such an embodiment, an ultrasonic
transmitter 168 under control of the controller 130 generates a
modulated signal on line 170 that is emitted by ultrasonic
transducer 138. As previously discussed, an ultrasonic signal

10 efficiently passes through the body fluids and tissues and as such
is a preferred communication means for communication between
devices implanted within the patient's body, e.g., other
microstimulators 100, and suitable for communication with external
devices in contact with the patient's skin.

15 The use of magnetic or ultrasonic communication,

i.e., transmitter and receiver, means are not mutually exclusive
and in fact a preferred implanted device includes both. For
example as shown in FIG. 3A, a clinician's programmer 172 (a device
for primarily programming the operation of the implanted devices

20 100), can communicate with a microstimulator 100a using a modulated
magnetic signal from magnetic emitter 190 and periodically receive
a modulated magnetic signal from microstimulator 100a reflecting
its battery status. While this magnetic means of communication is
preferable during a charging mode, a patient control unit 174

25 (e.g., a device in direct contact with the skin, typically in the
form of a "wrist watch", primarily used for monitoring the status
of the embedded devices 100) will preferably communicate using
ultrasonic means. Additionally, communication between implanted
microstimulators 100 is also desirable, e.g., in a master-slave or

30 transponder-slave configuration. For these modes, ultrasonic means
are preferable since ultrasonic signals efficiently pass through
the body fluids.

The battery-powered device 100 of the present
invention is preferably configurable to operate in a plurality of

35 operation modes, e.g., via a communicated command signal.
Alternatively, preconf igured, battery-powered, implanted devices

WO 98/37926 PCT/US98/03687

are also considered to be within the scope of the present
invention. In a first operation mode, device 100 (sized so that it
can be implanted using a hypodermic needle type insertion tool 176)
is configured to be a stimulator, hence such a device is referred
5 to as a microstimulator (e.g., 100a and 100b) . In this embodiment,
the controller 130 commands stimulation circuitry 110 to generate
a sequence of drive pulses through electrodes 112 to stimulate
tissue, e.g., a nerve, proximate to the implanted location of the
microstimulator 100a or 100b. In operation, a programmable pulse

10 generator 178 and voltage multiplier 180 are configured with
parameters (see Table I) corresponding to a desired pulse sequence
and specifying how much to multiply the battery voltage (e.g., by
summing charged capacitors or similarly charged battery portions)
to generate a desired compliance voltage V... A first FET 182 is

15 periodically energized to store charge into capacitor 183 (in a
first direction at a low current flow rate through the body tissue)
and a second FET 184 is periodically energized to discharge
capacitor 183 in an opposing direction at a higher current flow
rate which stimulates a nearby nerve. Alternatively, as disclosed

20 in the previously incorporated references, electrodes can be
selected that will form an equivalent capacitor within the body
tissue .
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Current :

Charging currents :
Current Range:

Compliance Voltage:

Pulse Frequency ( PPS )

Pulse Width:

Burst On Time (BON) :

Burst Off Time (BOF) :

continuous current charging of
storage capacitor

1, 3, 10, 30, 100, 250, 500 ua

0.8 to 40 ma in nominally 3.2%
steps

selectable, 3-24 volts in 3 volt
steps

1 to 5000 PPS in nominally 30%
steps

5 to 2000 us in nominally 10% steps

1 ms to 24 hours in nominally 20%
steps

Triggered Delay to BON: either selected BOF or pulse width

Burst Repeat Interval

Ramp On Time:

Ramp Off Time:

1 ms to 24 hours in nominally 20%
steps

0.1 to 100 seconds (1, 2, 5, 10
steps )

Table I - Stimulation Parameters

While the desirability of being able to stimulate
tissue for a prolonged period of time has been described, failure
modes can also be envisioned. Therefore, a magnet sensor 186

(preferably a semiconductor, e.g., Hall-effect, sensor) is
preferably coupled to the controller 130 which can be used to
modify the function, e.g., discontinue operation, of the
microstimulator 100 when exposed to a static magnetic field. Such
a magnet sensor 186 can be activated by placing a safety magnet 187

(to generate the static magnetic field) proximate to the
microstimulator 100 at the patient's skin 12. Additionally, it is
desirable that a microstimulator 100 cease operation when its
battery voltage reaches a lower limit (or exceeds a maximum

WO 98/37926 PCT/US98/03687

temperature) as determined by the charging circuitry 122 and
communicated to the controller circuitry 106. This ensures
reliable operation as well as prolonging the useful life of the
rechargeable battery 104. When this low voltage condition is
5 detected, a preferred device periodically emits a corresponding
status signal (preferably in response to remotely generated
interrogation/polling signal) to request that the battery be
recharged.

In a next operation mode/ the battery-powered

10 implantable device 100 can be configured to operate as a sensor,
i.e., a microsensor 100c, that can sense one or more physiological
or biological parameters in the implanted environment of the
device. In a preferred mode of operation, a system controller,
e.g., an externally located device or an implanted device,

15 periodically request the sensed data from each microsensor 100c
using its ID stored in address storage 108, and responsively sends
command signals to microstimulators, e.g., 100a and 100b, adjusted
accordingly to the sensed data. For example, a sensor 188 can be
coupled to the electrodes 112 to sense or otherwise used to measure

20 a biological parameter, e.g., temperature, glucose level, or 0 2
content. Additionally, the ultrasonic transducer 138 or the coil
116 can be used to respectively measure the magnetic or ultrasonic
signal magnitudes (or transit durations) of signals transmitted
between a pair of implanted devices and thus determine the relative

25 locations of these devices. This information can be used to
determine the amount of body movement, e.g., the amount that an
elbow or finger is bent, and thus form a portion of a closed loop
motion control system.

In another operation mode, the battery-powered

30 implantable device 100 can be configured to operate as a
transponder, i.e., a microtransponder lOOd. In this operation
mode, the microtransponder receives (via the aforementioned
receiver means, e.g., magnetic or ultrasonic) a first command
signal from a system controller and retransmits this signal

35 (preferably after reformatting) to other implanted devices (e.g.,
microstimulators, microsensors , and/or microtransponders ) using the

WO 98/37926 PCTYUS98/03687

aforementioned transmitter means {e.g., magnetic or ultrasonic).
While a microtransponder may receive one mode of command signal,
e.g., magnetic, it may retransmit the signal in another mode, e.g.,
ultrasonic. For example, clinician's programmer 172 may emit a
5 modulated magnetic signal using a magnetic emitter 190 to
program/command the implanted devices. However, the magnitude of
the emitted signal may not be sufficient to be successfully
received by all of the implanted devices. As such, a

microtransponder lOOd may receive the modulated magnetic signal and

10 retransmit it (preferably after reformatting) as a modulated
ultrasonic signal which can pass through the body with fewer
restrictions. In another exemplary use, the patient control unit
174 may need to monitor a microsensor 100c in a patient's foot.
Despite the efficiency of ultrasonic communication in a patient' s

15 body, an ultrasonic signal could still be insufficient to pass from
a patient's foot to a patient's wrist (the typical location of the
patient control unit 174) . As such, a microtransponder lOOd could
be implanted in the patient's torso to improve the communication
link .

20 In still another operation mode, a battery-powered

device can be configured to operate as a master system controller
that can alter the operation of the other implanted devices, i.e.,
microstimulators and microsensors , in a closed loop mode of
control .

25 FIG. 4 shows the basic format of an exemplary message

for communicating with the aforementioned battery-powered devices
100, all of which are preconf igured with an address (ID),
preferably unique to that device, in their identification storage
108 to operate in one or more of the following modes (1) for nerve

30 stimulation, i.e., as a microstimulator , (2) for biological
parameter monitoring, i.e., as a microsensor, and/or (3) for
retransmitting received signals after reformatting to other
implanted devices, i.e., as a microtransponder. The command
message 192 is primarily comprised of a (1) start portion 194 (one

35 or more bits to signify the start of the message and to synchronize
the bit timing between transmitters and receivers, (2) a mode

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portion 196 (designating the operating mode, e.g., stimulator,
sensor, transponder, or group mode) , (3) an address (ID) portion
198 (corresponding to either the identification address 108 or a
programmed group ID), (4) a data field portion 200 (containing
command data for the prescribed operation) , (5) an error checking
portion 202 (for ensuring the validity of the message 192, e.g., by
use of a parity bit), and (6) a stop portion 204 (for designating
the end of the message 192) . The basic definition of these fields
are shown below in Table II. Using these definitions, each device
can be separately configured, controlled and/or sensed as part of
a system for controlling one or more neural pathways within a
patient' s body.

MODE

00
01
02
03

Stimulator
Sensor
Transponder
Group

Data Field Portion

ADDRESS (ID)
8 bit identification address
8 bit identification address
4 bit identification address
4 bit group identification
address

Program/ Stimulate
Parameter /
Precon figuration
Select

Parameter Value

select operating mode

select programmable parameter in
program mode or preconf igured
stimulation or sensing parameter in
other modes
= program value

Table II - Message Data Fields

Additionally, each device 100 can be programmed with
35 a group ID (e.g., a 4 bit value) which is stored in its
configuration data storage 132. When a device 100, e.g., a
microstimulator, receives a group ID message that matches its
stored group ID, it responds as if the message was directed to its

identification address 108.

Accordingly, a plurality of

40 microstimulators, e.g., 100a and 100b, can be commanded with a

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single message. This mode is of particular use when precise timing
is desired among the stimulation of a group of nerves.

FIG. 5A shows a side view of a microst imulator
100 made in accordance with the present invention which includes
5 battery 104 for powering the circuitry within. The battery 104
conveniently fits within a sealed elongate housing 206 (preferably
hermetically sealed) which encases the microstimulator 100. In a
preferred device 100, the axial dimension 208 is less than 60 mm
and the lateral dimension 207 is less than 6 mm.

10 For the embodiment shown in FIG. 5A, the battery

104 is preferably housed within its own battery case 209, with the
battery terminals comprising an integral part of its case 209 (much
like a conventional AA battery) . Thus, the sides and left end of
the battery 104 (as oriented in FIG. 5A) may comprise one battery

15 terminal 210, e.g., the negative battery terminal, and the right
end of the battery 104 may comprise the other battery terminal,
e.g., the positive battery terminal used as the output terminal
128. Advantageously, because such a battery case 209 is
conductive, it may serve as an electrical conductor for connecting

20 an appropriate circuit node for the circuitry within the
microstimulator 100 from one side of the battery to the other.
More particularly, for the configuration shown in FIG. 5A, the
battery terminal 210 may serve as a ground point or node for all of
the circuitry housed within the device housing 206. Hence, stem

25 212 from the electrode 112a on the left end of the microstimulator
100, which from an electrical circuit point of view is simply
connected to circuit ground, may simply contact the left end of the

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battery 104. Then, this same circuit ground connection is made
available near or on the rim of the battery 104 on its right side,
near one or more IC chips 216 (preferably implementing the device's
power consuming circuitry, e.g., the controller 106 and stimulation
5 circuitry 110) on the right side of battery 104 within the right
end of the housing 206. By using the conductive case 209 of the
battery 104 in this manner, there is no need to try to pass or fit
a separate wire or other conductor around the battery 104 to
electrically connect the circuitry on the right of the device 100

10 with the electrode 112a on the left side of the device 100.

FIG. 5B shows a battery powered microstimulator
100' that is substantially the same as the device 100 shown in FIG.
5A except that the microstimulator 100 1 includes internal coupling
capacitor 183 (used to prevent DC current flow through the body

15 tissue) . The internal coupling capacitor 183 is used for the
embodiment shown in FIG. 5B because both of the microstimulator
electrodes 112a and 112b used by the microstimulator 100 1 are made
from the same material, iridium. In contrast, the electrodes 112a
and 112b for the microstimulator 100 shown in FIG. 5A are made from

20 different materials, and in particular from iridium (electrode
112b) and tantalum (electrode 112a) , and such materials inherently
provide a substantial capacitance between them, thereby preventing
DC current flow. See, e.g., col. 11, lines 26-33, of U.S. Patent
No. 5,324,316.

25 FIGS. 5C and 5D show two side cutaway views of the

presently preferred construction of the sealed housing 206, the
battery 104, the capacitor 183 and the circuitry (implemented on

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one or more IC chips 216) contained within. In this presently
preferred construction, the housing 206 is comprised of an
insulating ceramic tube 2 60 brazed onto a first end cap forming
electrode 112a via a braze 262. At the other end of the ceramic
5 tube 260 is a metal ring 264 that is also brazed onto the ceramic
tube 260. The circuitry within, i.e., the capacitor 183, battery
104, IC chips 216, and a spring 266 is attached to an opposing
second end cap forming electrode 112b. A drop of conductive epoxy
is used to glue the capacitor 183 to the end cap 112a and is held

10 in position by spring 266 as the glue takes hold. Preferably, the
IC chips 216 are mounted on a circuit board 268 over which half
circular longitudinal ferrite plates 270 are attached. The coil
116 is wrapped around the ferrite plates 270 and attached to IC
chips 216. A getter 272, mounted surrounding the spring 266, is

15 preferably used to increase the hermeticity of the device 100 by
absorbing water introduced therein. An exemplary getter 272
absorbs 70 times its volume in water. While holding the circuitry
and the end cap 112b together, one can laser weld the end cap 112b
to the ring 264. Additionally, a platinum, iridium, or platinum-

20 iridium disk or plate 274 is preferably welded to the end caps of
the device 100 to minimize the impedance of the connection to the
body tissue.

The battery 104 is described more fully below in
connection with the description of FIGS. 6-8. Preferably, the
25 battery 104 is made from appropriate materials so as to provide a
power capacity of at least 1 microwatt-hour, preferably constructed
from a battery having an energy density of about 240 mW-Hr/cm 3 . A

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Li-I battery advantageously provides such an energy density.
Alternatively, an Li-I-Sn battery provides an energy density up to
360 mW-Hr/cm 3 . Any of these batteries, or other batteries
providing a power capacity of at least 1 microwatt-hour may be used
5 with the present invention.

The battery voltage V of an exemplary battery
is nominally 3.6 volts, which is more than adequate for operating
the CMOS circuits which are used to implement the IC chip(s) 216,
and/or other electronic circuitry, within the device 100. The

10 battery voltage V, in general, is preferably not allowed to
discharge below about 2.55 volts, or permanent damage may result.
Similarly, the battery 104 should preferably not be charged to a
level above about 4.2 volts, or else permanent damage may result.
Hence, the aforementioned charging circuit 122 is used to avoid any

15 potentially damaging discharge or overcharge.

Turning next to FIGS. 6-9, additional details
concerning the battery 104 used within the implantable device 100
are presented. Basically, the battery 104 may take many forms, any
of which may be used so long as the battery can be made to fit

20 within the small volume available. As previously discussed, the
battery 104 may be either a primary battery or a rechargeable
battery. A primary battery offers the advantage of a longer life
for a given energy output but presents the disadvantage of not
being rechargeable (which means once its energy has been used up,

25 the device 100 no longer functions) . However, for many
applications, such as one-time-only muscle rehabilitation regimens
applied to damaged or weakened muscle tissue, the device 100, e.g.,

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a microstimulator , need only be used for a short time (after which
it can be explanted and discarded, or simply left implanted as a
benign medical device) . For other applications, a rechargeable
battery is clearly the preferred type of energy choice, as the
5 tissue stimulation provided by the microstimulator is of a
recurring nature.

The considerations relating to using a
rechargeable battery as the battery 104 of the implantable device
100 are presented, inter alia, in the book, Rechargeable Batteries,

10 Applications Handbook , EDN Series for Design Engineers, Technical
Marketing Staff of Gates Energy Products, Inc. (Butterworth-
Heinemann 1992). The basic considerations for any rechargeable
battery relate to high energy density and long cycle life. Lithium
based batteries, while historically used primarily as a

15 nonrechargeable battery, have in recent years appeared commercially
as rechargeable batteries. Lithium-based batteries typically offer
an energy density of from 240 mW-Hr/cm : ' to 360 mW-Hr/cm 3 . In
general, the higher the energy density the better, but any battery
construction exhibiting an energy density resulting in a power

20 capacity greater than 1 microwatt-hour is suitable for the present
invention.

One of the more difficult hurdles facing the use
of a battery 104 with the device 100 of the present invention
relates to the relatively small size or volume inside the housing
25 206 within which the battery must be inserted. A typical device
100 made in accordance with the present invention will preferably
be no larger than about 60 mm long and 6 mm in diameter and

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includes even smaller embodiments, e.g., 15 mm long with an O.D. of
2.2 mm (resulting in an I.D. of about 2 mm). When one considers
that only about H to H of the available volume within the device
housing 206 is available for the battery, one begins to appreciate
5 more fully how little volume, and thus how little battery storage
capacity, is available for the device 100.

The device 100, e.g., a micros timulator, of the
present invention is designed to generally consume only small
amounts of power. The principal power drain for power consuming

10 circuitry of the microstimulator 100 is the stimulating current
that is applied to the tissue in contact with the electrodes 112.
A typical stimulating current is shown in FIG. 10 which exhibits a
very low duty cycle. For example, an exemplary waveform for
providing an essentially continuous stimulation of a nerve may have

15 0.2 msec pulses (T ; .) that occur every 50 msec (TJ, i.e., at a 20
Hz rate.

If such current pulses have a peak value of 5 ma
(I p ), and are delivered at a potential of 3.6 volts (V), then the
peak output power (P), in units of watts (W) , delivered by the
20 device is

P = IV

= (5 ma) (3 . 6 v) = 18 mW
and the average output power, which is a function of the duty
cycle, is

25 P(ave)= 18 mW x .2/50 = 0.072 mW = 72 uW.

If a nominal sized microstimulator is employed,
having a length L of 15 mm and an I.D. of 2 mm (so the radius, r,

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is 1 mm) , and assuming that 1/3 of the available length, or 5 mm,
is available for the battery (L B ) , the battery would have a volume
of

Vol BAT = nr 2 L B

= n (1 mm) 2 (5 mm) (1 cmVlOOO mm 3 )
= 0.0157 cm 3 .

Assuming the battery is fabricated from
materials that exhibit an energy density of 240 mW-Hr/cm 3 , it is
thus seen that a fully charged battery can support a nominal load
of 72 uW (0.072 mW) for a time period of:

(240 mW-Hr/cm 3 ) (0.0157 cm 3 ) / ( . 072 mW)=52.3 Hrs
which is approximately 2.2 days. If a safety factor of at least
two is employed, the battery should thus be recharged each day.

However, other applications may require a
significantly smaller drive currents (e.g./ 1 via) albeit at a
higher duty cycle, e.g., bone growth stimulation, or possibly
larger drive currents (e.g., 40 ma) at a smaller duty cycle, e.g.,
bladder stimulation or other applications that may only require
nerve stimulation for minutes per day. A value of 1 microwatt-hour
has been chosen as a minimum specification for a battery used in
embodiments of the present invention. However, as shown above,
embodiments of the present invention can include batteries with
significantly higher capacities and thus such embodiments can
encompass a larger range of applications.

Turning next to FIGS. 6A and 6B, the manner in
which the battery plates or electrodes may be connected in parallel
or in series is illustrated. A parallel connection of interleaved

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or stacked positive electrodes 218 with negative electrodes 220^is
illustrated in FIG. 6A. A series connection of such interleaved
electrodes is shown in FIG. 6B. In general, the resistance
associated with the parallel connection is lower than the
5 resistance associated with the series connection, which means that
the time constant of the battery, i.e., the time it takes to
discharge or charge the battery at a given current level, will be
higher or longer for the series connection than it is for the
parallel connection. While the discharge time constant is
10 generally not of concern for purposes of the present invention
(because so little current is drained from the battery when in
use) , the charge time constant may be important (because that
determines, at least in part, how long it takes to recharge the
battery) .

15 FIG. 7A depicts a typical cylindrical shape for

the battery 104. In general, such shape has a lateral dimension or
diameter D and an axial dimension or length L R . However, it is
recognized that other shapes are possible and potentially
advantageous. For example, a rectangular or prismatic shaped

20 battery can also be used, including ones that may extend the full
length of the housing 206, with the power consuming circuitry,
e.g., the controller 106 the stimulation circuitry 110, mounted in
the surrounding interior areas of the housing 206.

The electrodes used within the battery 104 are

25 arranged in pairs, and have a general relationship as shown in FIG.
7B where the electrodes or plates are mounted in an opposed spaced
relationship with an electrolyte disposed therebetween. A first

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electrode 222 is made from a first material, e.g., copper (Cu) . A
second electrode 224 is made from a second material, e.g., aluminum
(Al) . A polypropylene separator 226 separates the two electrodes.
The separator 226 physically separates and prevents the electrodes
5 from touching each other, thereby preventing electron current flow
between the electrodes, but has pores therein that allows ions to
pass therethrough, thus allowing ionic current flow between the
electrodes. A suitable electrolytic paste 228 surrounds the
electrode 222. Another suitable electrolytic paste 230 surrounds

10 the electrode 224. Suitable materials from which such electrolytic
pastes may be made are described in the literature. Typically, the
thickness of the electrode pair, X, including separator and
electrolytic paste, is on the order to 0.010 or 0.024 inches, where
the Cu and Al electrodes are each about 0.001 inches thick, the

15 separator 226 is about 0.001 inches thick or less, and the
electrolytic paste on each side of the electrode is about 0.002 to
.008 inches thick. The combination of the two electrodes 222 and
224, with separators 226, and electrolytic pastes 228 and 230 forms
an electrode layer 232. A battery is formed by efficiently placing

20 the electrode layer 232 in the available battery volume, and
attaching suitable current collectors (conductors) to the positive
electrode 222 and negative electrode 224 so that electrical contact
may be made therewith.

The various figures shown in FIGS. 8A-8F depict

25 various configurations that may be used to form the cylindrical
shaped battery 104 needed by the present invention. Each of the
individual figures shows a side sectional side view of the battery

• 4

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container below a cross-sectional view (as viewed, e.g., from the
top) of the container .

In FIG. 8A, a length of the electrode layer 222
and 224 is rolled in spiral fashion and inserted longitudinally
5 into a cylindrical-shaped container or case 234. Conductive wires
or tabs 236 and 238 are attached to the electrodes 222 and 224
respectively and serve as the battery terminals.

In FIG. 8B, a parallel-connected interleaved
stack of circular-shaped positive electrodes 222 and negative

10 electrodes 224 are laid into a conductive container 234. Separator
layers (not shown) are laid in-between the electrodes as required.
The positive electrodes 222 are each connected to a bus that
contacts the container 234. The negative electrodes 224 are each
connected to a bus that contact a conductive lid 239 of the

15 container 234. Alternatively, the negative electrodes 224 can be
connected to the bus that contacts the container and the negative
electrodes 224 can be connected to the bus that contacts the lid
239. Notches or cutouts 240 may be placed in each electrode to
make a via for the buses that connect the electrodes to the

20 container 234 or lid 239. An insulating ring 241 assures that the
lid 239 does not short or touch the case 234. The container 234
and lid 239 thus function as the battery terminals.

FIG. 8C illustrates a series-connected
interleaved stack. Except for the series connection, the

25 arrangement shown in FIG. 8C is the same as that shown in FIG. 8B.

FIG. 8D shows a parallel-connected interleaved
vertical stack of rectangular electrode strips, of varying width.

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The negative electrodes 224 are each connected to the lid 239. The
positive electrodes 222 are each connected to the container 234.
The container 234 and the lid 239 thus serve as the battery
terminals .

5 FIG. 8E shows a parallel-connected concentric

electrode configuration where the electrodes 222 and 224 comprise
concentric tubes of different diameters that fit inside of each
other .

FIG. 8F shows a wire electrode embodiment where

10 the electrodes 222 and 224 are realized from a length of wire
(approximately L B ) made from the appropriate material, e.g., Cu or
Al, are positioned in an array such that the negative electrodes
224 are adjacent positive electrodes 222. Separator sleeves 226'
are placed over the electrode wires, e.g., the negative electrode

15 wires. The appropriate electrolytic paste fills the voids around
each of the respective electrodes. As required, the separator 226 ?
keeps the appropriate electrolytic paste around the appropriate
electrode, and prevents the other electrolytic paste from coming
near such area. The negative wires 224 are attached to the bottom

20 of the container 234, and the positive wire electrodes 222 are
attached to the lid 239.

FIG. 8G shows a parallel-connected cylindrical
electrode embodiment, similar to FIG. 8E, but wherein each
cylindrical electrode includes a gap or slit 242; with the

25 cylindrical electrodes 222 and 224 on each side of the gap 242
forming a common connection point for tabs 24 4 and 24 6 which serve
as the electrical terminals for the battery. The electrodes 222

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and 224 are separated by a suitable separator 248. The gap 242
minimizes the flow of eddy currents in the electrodes. For the
embodiment shown in FIG. 8G, there are four concentric cylindrical
electrodes 222, the outer one (largest diameter) of which may
5 function as the battery case 234, and three concentric electrodes
224 interleaved between the electrodes 222, with six concentric
cylindrical separator layers 248 separating each electrode 222 or
224 from the adjacent electrodes.

It is generally preferable to minimize the flow of

10 eddy currents in the battery which could result in heat or
otherwise shunting out a portion of the magnetic signal having a
modulated command signal portion. As such, by not forming a
battery with plates which form closed conductive loops, e.g., the
configurations shown in FIG. 8A-8D and 8F, the eddy currents are

15 minimized. However, circumstances can be envisioned where heating
is desired in which case the embodiment of FIG. 8E may be desired.

Turning next to FIG. 9A, one manner in which
inexpensive electrodes may be formed for a series-connected
electrode stack, such as that depicted in FIG. 8C, is illustrated.

20 One set of electrodes 250 may be stamped and cut, e.g., from a
0.002 inch thick sheet, in a suitable pattern, such as that shown.
A complementary set of electrodes 252 may likewise be stamped and
cut as shown. Each set of electrodes includes the basic circular
shaped electrode connected by a suitable tab 254. The tabs 254 are

25 offset from one electrode to the next. The electrode sets are then
folded and interleaved, so that the offset tabs 254 do not
interfere with each other, as depicted in FIG. 9B . Each of the

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electrode sets 250, 252 is then inserted into the container 234,
with a separator sleeve being inserted over one of the electrode
sets, with an appropriate electrical connection being made between
each electrode set and corresponding battery terminals.
5 While the invention herein disclosed has been

described by means of specific embodiments and applications
thereof, numerous modifications and variations could be made
thereto by those skilled in the art without departing from the
scope of the invention set forth in the claims. For example, while

10 primarily magnetic and ultrasonic means of communication have been
discussed, other communication means are possible. In an
alternative embodiment, implantable devices 100 can communicate via
conduction, i.e., modulated sub-stimulation- threshold current
pulses (pulses which do not stimulate the muscles or nerves)

15 emitted through the electrodes, infrared, or when an implanted
device is implanted just under the skin, translucent optical means
can be used. Additionally, other means can be used to charge the
battery within the implanted device including optical (e.g., solar
cells) and mechanical devices or, alternatively, a nuclear energy

20 implementation can be used to form a suitable primary battery.
//
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25 //
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CLAIMS

We claim:

1. A device configured for implantation beneath the
skin of a patient's body, said device comprising:

a sealed elongate housing having an axial
dimension of less than 60 mm and a lateral dimension of less than
6 mm;

power consuming circuitry at least partially
disposed in said housing having at least one power input terminal;

a power source having at least one power output

terminal ;

said power source having a capacity of at least
1 microwatt-hour; and

means electrically coupling said power output
terminal to said power input terminal for delivering electrical
power to said circuitry.

2. The device of claim 1 wherein said power source
comprises a battery including:

a case;

a first conductive plate mounted in said case;

a second conductive plate mounted in said case
in opposed spaced relationship relative to said first plate;

an electrolyte disposed between said first and
second plates; and wherein

said plates are configured to minimize eddy

currents therein.

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3. The device of claim 2 further including a
charging circuit for producing a charging current in response to
remotely produced electromagnetic energy; and

means applying said charging current to said

5 battery.

4. The device of claim 3 further including:

a coil positioned outside of a patient's body;
means for energizing said coil with an AC signal
10 to produce an alternating magnetic field for supplying energy to
said charging circuit.

5. The device of claim 1 wherein said power
consuming circuitry includes:
15 a controller;

address storage means for storing an
identification address ;

an input/output transducer; and

a data signal receiver for receiving a command
20 data signal identifying said stored address for selectively
actuating said input/output transducer.

6. The device of claim 5 wherein said data signal
receiver includes a coil responsive to a command data signal
25 defined by a modulated magnetic field.
//
//

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7. The device of claim 5 wherein said data signal
receiver includes a transducer responsive to a command data signal
defined by a modulated ultrasonic signal.

5 8. The device of claim 5 wherein said power

consuming circuitry further includes a data signal transmitter for
transmitting a data signal.

9. The device of claim 8 wherein said transmitter
10 includes means for transmitting a data signal in the form of a

modulated magnetic field.

10. The device of claim 8 wherein said transmitter
includes means for transmitting a data signal in the form of a

15 modulated ultrasonic signal.

11. The device of claim 5 wherein said input/output
transducer comprises at least one electrode configured to produce
an electrical current for stimulating tissue; and wherein

20 said controller supplies a sequence of drive

pulses to said electrode when said input/output transducer is
actuated.

12. The device of claim 11 wherein said controller
25 is responsive to said command data signal to control one or more

characteristics of said drive pulses.
//

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13. The device of claim 11 further including:

a sensor coupled to said controller responsive
to a static magnetic field; and wherein

said controller is configured to modify the
5 function of said device in response to a static magnetic field
detected by said sensor.

14. The device of claim 11 further including a
capacitor mounted in said housing for coupling said drive pulses to

10 said electrode.

15. The device of claim 8 wherein said input/output
transducer comprises at least one electrode; and further including
means for generating a data signal representative of an electrical

15 signal conducted by said electrode.

16. The device of claim 8 further including means
for generating a data signal representative of the status of said
power source.

17. The device of claim 8 further including means
for causing said transmitter to transmit a data signal related to
said command data signal received by said data signal receiver.
//

25 //
//
//

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18. The device of claim 8 wherein said device is
configurable via a command data signal identifying said stored
address to selectively operate to (1) supply a sequence of drive
pulses to said input/output transducer, (2) monitor an electrical
5 signal from said input/output transducer, and/or (3) cause said
data signal transmitter to transmit a data signal related to said
command data signal received by said data signal receiver.
//
//

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//

15 //
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//

20 //
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//

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19. A device configured for implantation beneath the
skin of a patient's body, said device comprising:

a sealed elongate housing having an axial
dimension of less than 60 mm and a lateral dimension of less than
5 6 mm;

power consuming circuitry at least partially
disposed in said housing having at least one power input terminal;

a rechargeable battery having at least one power

output terminal;

10 said rechargeable battery having a capacity of

at least 1 microwatt-hour; and

means electrically coupling said power output
terminal to said power input terminal for delivering electrical
power to said circuitry.

20. The device of claim 19 wherein said battery

comprises :

a case;

a first conductive plate mounted in said case;
20 a second conductive plate mounted in said case

in opposed spaced relationship relative to said first plate;

an electrolyte disposed between said first and
second plates; and wherein said plates are configured to minimize
eddy currents therein.
25 //
//
//

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21. The device of claim 19 further including a
charging circuit for producing a charging current in response to
remotely produced electromagnetic energy; and

means applying said charging current to said

5 battery.

22. The device of claim 21 further including:

a coil positioned outside of a patient's body;
means for energizing said coil with an AC signal
10 to produce an alternating magnetic field for supplying energy to
said charging circuit.
//
//
//

15 //

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//
//

20 //
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23. A charger for providing an alternating magnetic
field to one or more electrically-powered devices implanted beneath
the skin of a patient's body wherein each of said electrically-
powered devices is powered by a rechargeable battery mounted within
each said device, said recharger comprising:

a coil configured for mounting external to said
patient's body, proximate to one or more of said electrically-
powered devices; and

a controller for periodically providing an AC
signal to energize said coil; and wherein

said controller additionally includes
communication means for periodically providing a control signal to
said electrically-powered devices to selectively interrogate the
status of said rechargeable battery mounted within and receiving a
status signal in response thereto.

24. The charger of claim 23 wherein said
communication means comprises amplitude modulating said AC signal
with said control signal and receiving an AC signal amplitude
modulated with said status signal in response thereto.

25. The charger of claim 23 additionally comprising
a transducer capable of emitting a modulated output signal and
receiving a modulated input signal; and wherein said communication
means comprises modulating the output of said transducer with said
control signal and receiving an input signal modulated with said
status signal in response thereto.

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4/13

3 *

i <

9 —J

p: f= °

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6/13

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9/13

PARALLEL

FIG. 6A

218'

SERIES

FIG. 6B

104

FIG. 7A

FIG. 7B

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FIG. 8D

FIG. 8E

FIG. 8F

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FIG. 8G

FIG. 9B

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INTERNATIONAL SEARCH REPORT

International application No.
PCT7US9S/03687

A. CLASSIFICATION OF SUBJECT MATTER

IPC(6) :A61N 1/36
US CL :607/61

Ac cording to International Patent Classification (IPC) or to both national classification and IPC

a FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)

U.S. : 607/33,2, 61

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)

C. DOCUMENTS CONSIDERED TO BE RELEVANT

Category*

Citation of document, with indication, where appropriate, of the relevant passages

Relevant to claim No.

A
A
A

US 5,405,367 A (SCHULMAN et al) 11 April 1995, Abstract.
US 5,324,316 A (SCHULMAN et al) 28 June 1994, Abstract
US 5,591,217 A (BARRERAS) 07 January 1997, Abstract

1-25
1-25
1-25

| | Further documents are listed in the continuation of Box C. | | See patent family annex.

• Special categories or cited documenti: "T" later document published after tha international filing date or priority

date and act in conflict with the application but cited to understand
*A" document denning the general suite of the art which is not considered tha principle or theory underlying the invention
to be of particular relevance

. , _,. -X' document of particular relevance; the claimed invention cannot be
•E* earlier document published on or after the international filing date considered novel or cannot be considered to involve an inventive step

•L- document which may throw doubt, on priority elaim(s) or which is whets *• docuroont » takmn ,lon8

cited to establish the pubUcation data of another citation or other , y . documimt of particu l„ relevance; the claimed indention cannot be
special reason las apccuiedj considered to involve an inventive step when the document is

•O' document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such combination
maaru ' being obvious to a person skilled in the art

"P* document publuhod prior to the international filing date but later then document member of the same patent family

Date of the actual completion of the international search
25 APRIL 1998

Date of mailing of the international search report

% 0 MAY 1998

Name and mailing address of the ISA/US
Commissioner of Patents and Trademarks
Box PCT

Washington. D.C. 20231 ^
Facsimile No. (703) 305-3230

Authdj^ed offie^<\ f

X^SCOTT tSETZOW
telephone No. 703-308-2997

y r § r

Form PCT/ISA/210 (second shect)(July 1992)*

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Full text of "USPTO Patents Application 10597633"

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